1. Industrial Field of the Invention
The present invention relates to a fuel vapor processing apparatus which is able to detect abnormality of a fuel tank or the like in an automobile.
2. Description of Related Art
Japanese Utility Model Unexamined Publication No. 3-17169 discloses a fuel vapor purge system in a fuel vapor processing apparatus of a fuel tank in which fuel vapor in the fuel tank is supplied to a fuel vapor collecting canister and absorbed/collected by an absorbent filled in the canister, and the absorbed fuel in the canister is introduced, via a purge line, to the downstream of a suction air throttle valve in a suction air passage. In this publication, there is proposed a self-diagnosis device of the fuel vapor purge system in the fuel vapor processing apparatus of the fuel tank, comprising means for judging whether or not the fuel vapor purge system is in a range for fuel purge, means for detecting the pressure in the purge line, and means for judging whether the system is normal or abnormal, on the basis of the pressure in the purge line which pressure is judged to be in the fuel-purge range or out of the range, by use of detection signals produced from the detecting means.
In the above-described conventional technique, self-diagnosis whether or not cracks exist in the purge line is carried out while an air port of the canister is kept open to communicate with the atmosphere. Consequently, it is impossible to detect abnormalities in a main body of the canister and the fuel tank. There has conventionally been a problem that abnormality all over the fuel vapor processing apparatus and piping portions cannot be detected.